A letter from the Rolling Stones that thanks police for providing security at a 1964 concert fell well below auction expectations, fetching £950.
The letter, signed by all five band members including the late Brian Jones, offers "sincere appreciation" to police in north London.
Dated 9 September 1964, it refers to security at a recent London gig. It had been suggested it would fetch £4,600.
The letter was sold at the Jubilee Auction Rooms in Pewsey, Wiltshire.
The letter is addressed to the officer in charge of "Finsbury Park Police Station", which did not exist.
It was forwarded by the Post Office to Highbury Vale Police Station, whose commander gave it to a young WPC - the letter's present owner.
"We would be grateful if you would thank the officers concerned on their behalf," it read.
The new owner of the letter is a collector from Swansea.
The Rolling Stones did not always have such cordial relations with Her Majesty's Constabulary.
Six months later, Mick Jagger, Bill Wyman and Jones were arrested and charged with urinating on the wall of an east London petrol station.
And in February 1964, Jagger and Keith Richards ("Richard" in the letter) were arrested and charged with drugs offences.